Clip ALL of the wire ties

Remove all the nuts from the pots

Remove the smaller PCB which supports the tube sockets. The easiest way to do this is by removing the tubes, then removing the black screws which hold the sockets to the chassis

Unplug all the power and output transformer leads. As you remove each lead mark the wire with masking tape and a Sharpie so you will know where to plug it back in when you are putting the amp back together. I just mark the terminal number on the lead

Remove all circuit board standoff screws

Using gentle pressure on the top of the circuit board press the board down making sure it is not getting hung up on any wires until all the pots have cleared the top of the chassis then pull the board to you to expose the underside. DO NOT PUT PRESSURE ON ANY COMPONENTS INCLUDING THE FILTER CAPS WHEN MOVING THE BOARD